Various support techniques are used in underground mining. In hard rock mining in South African gold mines, for example, a large diameter hole is drilled into a rock body whereafter a rock bolt is inserted into the hole. Full column grouting of the rock bolt is preferred to obtain superior performance. To achieve this objective without excessive use of steel, a tubular steel rock bolt is used. Typically, the tubular steel rock bolt is inserted into a borehole and is fixed in place using a grout or a resin mixture.
Normally, a capsule which contains resin components is placed in a borehole. The capsule is punctured when the rock bolt is inserted into the hole and the contents of the capsule are mixed by rotating the rock bolt. If the rock bolt is tubular, a leading end of the rock bolt must be closed to prevent the resin mix from flowing into an interior of the rock bolt. One way of sealing the tubular rock bolt is to deform the leading end, so that it is pointed. However, when this point penetrates the capsule, a so-called “finger gloving” effect may arise, when the bolt is rotated, which effect results in the resin not being adequately mixed or correctly distributed throughout the borehole.
If the leading end of the rock bolt is pressed flat and is thus closed, a chisel shape results. This helps to avoid “finger gloving” during resin mixing. However, the leading end will have a width which exceeds the width of a borehole—a feature which works against the adoption of this technique.
An object of the present invention is to provide a rock bolt which enables the aforementioned situation to be addressed.